Get hashed forgotten userIds in compliance with GDPR

Returns a hash for each <code>userId</code> currently forgotten by your project. Each forgotten <code>userId</code> is lowercased, trimmed, and hashed using SHA-256. This endpoint only works for userID-based and hybrid projects. For email-based projects, it returns an error.<br/><br/>Learn about <a href="https://support.iterable.com/hc/articles/29156459027348">identifying users by <code>userId</code> and <code>email</code></a>.<br/><br/><b>Rate limit</b>: 3 requests/second, per project.